1. Field of the Invention
The present invention relates to a color-unevenness inspection apparatus and method in which color unevenness of a color image or the like is inspected.
2. Description of the Related Art
Previously, for a color-unevenness inspection in a mass-production process for a display device that uses a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD) or the like capable of displaying a color image, a sensory test based on a comparison with a boundary sample has been mainly performed. This technique is carried out such that a display screen of the display device targeted for the inspection is directly viewed by a human being and therefore, this is an inspection close to actual use and also a simple and easy technique.
However, this technique relies largely upon the capabilities of individual inspectors and thus, quality of inspection varies depending on factors such as variations among the individual inspectors and the inspector's the degree of fatigue. Therefore, it is difficult to perform a stable inspection.
Under the circumstances, there have been proposed some techniques of objectively inspecting color unevenness without depending on the capability of the inspector. For example, there is a technique of inspecting color unevenness, by measuring a hue in each of plural points within a display screen by using a color imaging device or the like, in a state in which the entire display screen is set at white display. In this technique, the color unevenness is inspected according to the magnitude of a value representing a maximum color difference (ΔEuv* or ΔEab*) between a result of the measurement and a white display portion.
Specifically, for example, in Japanese Unexamined Patent Application Publications No. 01-225296, No. 03-101583 and No. 03-291093, a color and brightness at each of plural points within a display screen are measured, and the dispersion, a difference between a maximum value and a minimum value, and the like are standardized and used for a color-unevenness inspection. Further, for instance, in Japanese Unexamined Patent Application Publication No. 10-96681, attention is focused on the spatial size of an uneven color region and a region where a color is changed, and these are quantified and used for a color-unevenness inspection.